Some mobile devices have features for providing location-based services. For example, a mobile device can execute a pre-specified application program or present certain content when the mobile device enters or exits a geofence. The geofence can be defined by a point location and a radius. The point location can have a longitude coordinate and a latitude coordinate. The mobile device can determine that the mobile device has entered the geofence or exited the geofence by determining an estimated location of the mobile device and calculating a distance between the estimated location and the point location. Based on whether the calculated distance exceeds the radius of the geofence, the mobile device can determine whether the mobile device entered or exited the geofence. The mobile device can determine the estimated location, which also includes a longitude coordinate and a latitude coordinate, using a global satellite system (e.g., GPS) or cellular triangulation.